After a two year treetop protest, Huck (left) and Shem, two of the last four tree sitters remaining in what was once a grove of oaks and redwoods on the site of U.C. Berkeley's new sports complex, wave from their perch on Monday Sept. 8, 2008 in Berkeley, Calif.

Photo: Mike Kepka, The Chronicle

After a two year treetop protest, Huck (left) and Shem, two of the...

Image 2 of 3

A U.C. Berkeley police officer walks past the last standing tree near what was once a grove of oaks and redwoods on the site of U.C. Berkeley's new sports complex, wave from their perch on Monday Sept. 8, 2008 in Berkeley, Calif. After two years of protest 4 tree sitters still remain in the tree.

Photo: Mike Kepka, The Chronicle

A U.C. Berkeley police officer walks past the last standing tree...

Image 3 of 3

Ayr holds a 2-way radio for press who ask tree sitters Huck and Shem questions about their protest on Monday Sept. 8, 2008 in Berkeley, Calif.

The standoff between UC Berkeley and four tree-sitters outside Memorial Stadium intensified Monday as work crews prepared to remove the protesters from a stripped-down redwood.

Workers used bulldozers to clear and level the ground surrounding the redwood, one of two trees standing in the center of the grove after crews cut down 40 other trees over the weekend to make way for a $124 million sports training center.

"The university is preparing for what will we hope be a quick and safe extraction in the coming days," campus spokesman Dan Mogulof said. "We had hoped it wouldn't come to this. It's extremely unfortunate."

Mogulof did not say exactly when or how the university would act to remove the tree-sitters.

The protest began more than 21 months ago, on Dec. 1, 2006.

Last week, a state appeals court declined to block the university's construction plans after an Alameda County judge ruled against stadium neighbors, tree advocates and the city of Berkeley, who said UC had not adequately addressed the impact of the project.

Negotiations aimed at getting the sitters to come down on their own broke down Sunday night, and the university cut off the protesters' food and water supply at 9 a.m. Monday.

The tree-sitters have about a day's worth of food left, said Mogulof and Eric Eisenberg, a protest leader.

In their most recent demand, the tree-sitters said they would come down if the university gives $6 million to environmental and Native American groups, creates a public committee on campus land use, and allows protesters to use the stump from the oldest tree in the grove, which protesters called "Grandma," for a Native American drum.

The university offered to give protesters the stump and allowed them three two-hour meetings with high-ranking campus officials to discuss mitigating the loss of the oak grove, long-term plans for the southeast corner of campus and other related issues.

But UC will not pay $6 million, Mogulof said.

"It's a nonstarter," he said. "We're committed to dialogue but they have to come down first."

In July, the university hired a mediator to help negotiate with the tree-sitters and community over the athletic center. The mediator met with protesters and campus officials over the weekend, but talks ended after an apparent split among the protesters, Mogulof said.

"It appears the tree-sitters and their supporters could not come to an agreement within themselves," he said.

Eisenberg denied the claim.

"There's no split. Everyone's on board with our proposal," he said. "The university's saying there's a split because they don't want to negotiate with us. They're choosing confrontation over a peaceful resolution."

The occupied redwood must be removed in the next few days, UC officials said, because construction is expected to begin and the tree is in the footprint of the training center.

After the tree is removed, the university will bring in independent archaeologists to examine the site for artifacts. Construction is likely to begin shortly after that, with the center completed in about 2 1/2 years.

The athletic center will provide offices and training centers for about 500 staff and student athletes, including the Cal Bears football team and several women's teams that currently have no facilities.

Delays as a result of litigation are expected to boost construction costs by an estimated $20 million, officials said, and cost the university $750,000 in private security, police overtime, lights, fencing and other security costs.

On Monday, dozens of people gathered along Piedmont Avenue to witness what could have been the final day of the protest. Supporters of the four male tree-sitters spent their day drumming, praying and talking to the tree-sitters via cell phone. There were no arrests or injuries.